fletcherist · November 3, 2017 23:15 · Nov 3, 2017 · Nov 3, 2017
diff --git a/gistfile1.txt → blockchain.js b/gistfile1.txt → blockchain.js
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,67 @@
+// This is blockchain implementaion
+// Be careful — it doesn't work as expected actually :)
+const CryptoJS = require('crypto-js')
+
+class Block {
+  constructor(index, timestamp, data, previousHash = '0') {
+    this.index = index
+    this.previousHash = previousHash
+    this.timestamp = timestamp
+    this.data = data
+    this.hash = this.calculateHash()
+  }
+
+  calculateHash() {
+    return CryptoJS.SHA256([
+      this.index,
+      this.previousHash,
+      this.timestamp,
+      this.data
+      ].map(element => JSON.stringify(element)).join('')
+    ).toString()
+  }
+}
+
+class Blockchain {
+  constructor() {
+    this.chain = [this.createGenesisBlock()]
+  }
+
+  createGenesisBlock() {
+    return new Block(0, Date.now(), 'genesis block')
+  }
+
+  getLatestBlock() {
+    return this.chain[this.chain.length - 1]
+  }
+
+  addBlock(newBlock) {
+    newBlock.previousHash = this.getLatestBlock().hash
+    console.log('just added', newBlock)
+    this.chain.push(newBlock)
+  }
+
+  isValidChain() {
+    for (let i = 1; i < this.chain.length; i++) {
+      const currentBlock = this.chain[i]
+      const previousBlock = this.chain[i - 1]
+      if (currentBlock.hash !== currentBlock.calculateHash()) {
+        console.log(currentBlock)
+        console.log(currentBlock.calculateHash())
+        return false
+      }
+
+      if (currentBlock.previousHash !== previousBlock.hash) {
+        return false
+      }
+    }
+
+    return true
+  }
+}
+
+
+const blockchain = new Blockchain()
+blockchain.addBlock(new Block(1, Date.now(), { amount: 4 }))
+console.log(blockchain.isValidChain()) // WTF? why false damn it?
+console.log(blockchain)